QGIS Print Composer does not change from landscape to portrait orientation?
QGIS 2.x
There is an Orientation option in the Composition menu which allows you to switch between Portrait and Landscape:
Can't confirm this but I would guess that the Page Setup... are options for printing and not for visualising onscreen.
QGIS 3.x
To change the layout orientation, right-click on the layout and select Page Properties
. You can also change other various settings for the layout:
To solve this go View/Panel/Compostion. The composition panel will appear in the right sidebar of the Print Composer. It is non intuitive. The setting for this is in a very odd place indeed.
QGIS 2.14.3 Essen